The invention concerns a power assembly especially for automotive vehicles, of the type comprising an internal combustion engine.
In today's economy, the demand for energy is expanding and, at the same time, energy (fossil energy such a fuel or non fossil energy such as biofuel) is becoming rarer and consequently more expensive.
Automotive vehicles especially industrial vehicles rely on internal combustion engines using fuel as a source of energy. It is therefore important that internal combustion engines are as efficient as possible.
One of the options for improving the overall efficiency of automotive vehicles can consist in using engines of smaller capacity. Engine downsizing proves to be beneficial on many standpoints such as fuel consumption and exhaust emission. Engine downsizing is a viable option that has many benefits; however the limit is that a vehicle might be underpowered when facing unusually demanding operational circumstances (for example: acceleration phase or steep road) even if the said demanding operational circumstances might account for a small fraction of the vehicle operational life. That is why automotive vehicles are usually over dimensioned to face normal operational conditions.
In this technical context it is desirable to provide a power assembly especially for an automotive vehicle, having an internal combustion engine that can include additional power capacity to face peak operational conditions.
It is also desirable to provide a power assembly having an internal combustion engine wherein an additional power source is efficiently engine.
According to an aspect of the invention, a power assembly is provided, especially for an automotive vehicle, comprising a main internal combustion engine including an air intake line and an exhaust gas line.
According to an aspect of the invention, the power assembly further comprises a Brayton cycle system capable of providing additional power to the main internal combustion engine; the said Brayton cycle system include a gas compressor, a fuel burning heater and a turbine linked to the compressor so that 1) air is drawn into the compressor where it is pressurized, 2) the pressurized air is further heated by flowing through at least one heat exchanger where it exchanges heat with exhaust gases from the main internal combustion engine, 3) the heated and pressurized air is further heated by the fuel burning heater and 4) is thereafter expanded through the turbine where a first fraction of the work extracted by the turbine is used to drive the compressor and a second fraction of the work extracted by the turbine is used to bring additional energy.
The power assembly according to an aspect of the invention includes an internal combustion engine combined with a Brayton cycle system that can bring additional energy so as to meet a peak operational demand. The Brayton cycle system operates according to a known cycle that includes the following four phases: 1) compression, 2) heat addition, 3) expansion, 4) heat rejection. By incorporating a Brayton cycle system in an internal combustion engine, aspects of the invention makes a remarkably efficient use of some energy that is wasted in a conventional internal combustion engine. In a conventional internal combustion engine, the heat that is released in the combustion is mainly wasted. The overall efficiency of the Brayton cycle system is improved by the fact that the pressurized air is heated not only by flowing through the compressor but also by flowing through one or more heat exchangers where further energy in the form of heat is added to the pressurized air. A further beneficial aspect of the invention is that the Brayton cycle system does not require additional cooling capacity. Instead the Brayton cycle system uses some of the heat released in the combustion process.
Therefore, the power assembly according to an aspect of the invention shows significant benefits to an automotive vehicle and especially to an industrial vehicle insofar as:                a vehicle can be equipped with a downsized internal combustion engine that can rely on an additional power capacity provided by a Brayton cycle system,        the additional power capacity provided by a Brayton cycle system (i) makes an efficient use of the energy that is normally wasted in heat in an internal combustion engine and (ii) provokes limited disturbances in the overall architecture of the vehicle as it does not require additional cooling capacity.        
In an embodiment of the invention, the exhaust line is provided with a heat exchanger where energy in the form of heat from the internal combustion engine exhaust gas is transferred to the pressurized air that flows in the Brayton cycle system.
The heat exchanger in the exhaust line may be arranged upstream of a pollution control device, especially in the case of a device including a SCR catalytic converter, or downstream of said device, especially in the case of a device including a diesel particulate filter (DPF).
In another embodiment of the invention, the internal combustion engine includes an EGR line that recirculates a portion of the exhaust gas back to engine cylinders, the EGR line having an EGR heat exchanger where heat from the EGR gas is transferred to the pressurized air that flows in the Brayton cycle system. In this embodiment of the invention, the pressurized air that can benefit from the heat of the EGR gases which are/generally at a high temperature.
The additional power capacity can be conveniently achieved by an electromechanical device which is capable of converting the mechanical work into electrical energy and which is connected to the turbine.
Further, an electric motor powered by the electrical energy extracted by the electromechanical device can be connected to the vehicle driveline.
According to a further embodiment, a transmission device can connect the turbine to the vehicle driveline to transfer the work extracted by the turbine to the internal combustion engine.
The power assembly can comprise a control unit that includes capable of controlling the operation of the Brayton cycle system according to vehicular operational parameters. In operational terms, the control unit controls the operation of the fuel burning heater to turn it on or off and/or controls the amount of heat generated by the fuel burning heater.
In a preferred embodiment of the invention, the heated air and combustion products produced in the fuel burning heater flow through a pollution control component situated downstream of the turbine.
It is to be noted that the internal combustion engine can be suitably equipped with a turbocharger.
To comply with emission regulations, the heated air and combustion products produced in the burner flow through a pollution control component situated downstream of the turbine.
The power assembly according to an aspect of the invention concerns internal combustion engine can be equipped with a turbochanger and/or the internal engine is a diesel engine.